While some of the theories discussed are complex, the authors convey them in a clear and accessible manner, with the use of engaging pedagogical features, making this an ideal introduction to international relations theories. A new chapter on Critical Theory has been added to allow more coverage for this approach and alternative understandings, such as post-colonialism and environmentalism, have chapters devoted to them, unlike other textbooks. Chapters have also been updated to reflect recently published work and the case studies have been revisited to include considerations of new developments in world politics.